This project is concerned with a number of aspects of hormone biology including efforts ot elucidate hormonal mechanisms controlling membrane permeability, transport and contractile processes at the cellular and molecular levels. Within the framework of these goals we are investigating (1) the effect of changes in primary chemical structure on the conformation and biological activities of peptides, primarily neurohyphyseal hormones (NHH), (2) the nature of early events in the hydroosmotic action of vasopressin, (3) phenomena associated with modulation and termination of hormone action, (4) hypophysiotropic and other peptides active on the central nervous system, and (5) phenomena bearing on the possible application of NHH and their congeners as therapeutic agents in several clinical disorders. We plan to synthesize and assay for factor VIII (FVIII)-mobilizing and antidiuretic-pressor (A-P) activities, analogs of vasopressin with alterations in the NHH tail sequence (positions 7, 8 and 9); in this work we will continue to use methods developed by our group and others, now accepted as standard methodology, for solid-phase peptide synthesis and evaluation of FVIII coagulant activity and FVIII-related antigen. The objective of this study is to find vasopressin analogs with significant FVIII-mobilizing activity and little or no antidiuretic-pressor activity. In addition we plan a variety of other chemical and physiological studies among which are included the synthesis, labeling with tritium and purification of photoaffinity analogs of arginine vasopressin to be used for isolation, characterization and functional studies of vasopressin receptors (and the extension of the methodology we have already developed for photoaffinity labeling of hydroosmotic vasopressin receptors in the toad bladder to other target organs and other functions of vasopressin --- and to oxytocin, substance P, neurotensin and selected target organs of these latter peptides). We also plan to continue our studies of the solution conformation of peptides (1) by extending our conformation-locus methodology to higher diemensions, by considering couplings between vicinally located pairs of dissimilar nuclei (namely, 13C-1H and 15N-1H couplings), (2) by refining the analysis so that it can be used to determine conformations about the CAlpha-CBeta bonds of the various residues in oxytocin and the vasopressins and (3) by developing and adapting for peptide conformational analysis physical techniques in addition to NMR (such as Raman and infrared spectroscopy which can "freeze out" three-dimensional molecular structures).